Thermal relay



H. m 5 m 9 RW v 3 Q mm W ATTORNEY July 31, 1928.

C. AALBORG THERMAL RELAY Filed June 23, 1925 WITNESSES: iku

awn 5' Patented July 31, I928.

UNITED STATES PATENT OFFICE.

HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYIa-.

VANIA.

- THERMAL RELAY.

Application filed June as, 1925. Serial No. 38,968.

My invention relates to temperature control devices and particularly to thermal relays.

One ob'ect of my invention is to provide a relatively simple, compact and inexpensive thermally-responsive device.

Another ob ect of my invention is to provide a thermal relay in which the pressure between coo crating contact members shall be increasetf preparatory to causing them tobe disengaged with a snap action.

In practicing my invention, I prov de a thermally-responsive means and a resilient energy-storing member actuated thereby, having associated therewith a member whose shape is changed by the resilient member whereby engagement or disengagement of cooperating contact members is effected with a snap action.

In the single sheet of drawings,

4 Figure 1' is a top plan view of a device embodying my inventlon.

Fig. 2 is a view, in side elevation, thereof.

Fig. 3 is a view in section therethrough. taken on the line III-III of Fig. 1.

Fig. 4 is a top plan view of two cooperating toothed sector members.

Fig. 5 is a view in side elevation thereof.

Fig. 6 is a top plan view of a member of modified form associated with the device embodyin my invention, and

Fig l is a top plan view of a modified form of device embodying my invention, 11- lustrated schematically only.

Referring more particularly to Figs. to 5, inclusive, a thermal relay 11 comprises a suitable base member 12 that is preferably of electric-insulating material and that may be substantially circular in contour.

Two supporting members 13 and 14 are mounted in spaced relation on the base plate 12 and are constituted by metal rod members, the lower ends of which extend into the base 12 and are so mounted and held therein that they may have a turning movement relative thereto. The upper ends of the respective rods 13 and 14', are provided with a diametrally extending slot to receive one end of spirally wound. bimetallic elements 15 and 16. The ends of the members 15 and 16 are secured in the members 13 and 14 by any desired method, such as by brazmg or soldering or by a screw clamping means.

An energy-storing member 17, constituted by a spring member of substantially U- shape, is so located relatively to the bimetaL' lic elements 15 and 16 that the outer ends of the respective bimetallic members may be secured to the side portions of the member 17 b suitable rivets 18. The ends of the mem er 17 are made in the form of knife edges in order that a toggle member comprising .two arms 19 and 21 may be operatively associated therewith. The outer ends of the arms19 and 21 are made in expanded form and provided with a slot or groove to receive the knife-edge ends of the member 17. The inner ends of the arms 19 and 21 are so shaped as to permit of their being fpivotally connected by a pin 22.,

A pair 0 stationary contact members 23 and 24 are suitably mounted on the upper surface of the base member 12 and are severally provided with upstanding contact portions 25 and 26 that are normally operatively engaged by contact members 27 and 28 that are mounted on the arms 19 and 21 here shown as machine screws, each provided.

with a lock nut to permit of securing the contact screws in a predetermined position after they have been adjusted.

Means for adjusting the initial position of the two spirally wound-bimetallic members 15 and 16 whereby the operating. temperature thereof may be adjusted, comprises a member 29 having its lower surface secured against the upper surface of the base member 12 and having an upwardly extending portion that is provided with a screw threaded opening 31 extending therethrou h substantially parallel to thesurface of t e base plate 12. An adjusting screw 32 having a knurled head 33 extends through the opening 31 and has an annular groove 34 adjacent to the outer end thereof.

Toothed sectors 35 and 36 are secured to the respective supporting members 13 and 14, the members being brazed or soldered together in order that a turning movement of the members 35 and 36 may efi'ect a corresponding turning movement of the members 13 and 14 and of the inner standing '34 of the cess 38, thereb positions. of t e sector members the sup porting osts 13 and 14, and of the inner .ends of t e bimetallic members by a turning ""-movement of the screwthreaded member 32.

While I have illustrated a toggle. mem- .42 secured thereto. When the member 39 is knife edges on- .than on the member 17. It is understood her in Fi 1 of the drawing, I do not desire Fig. '6 illustrates a spring memb'er 39 that I 7 is initially bent to arcuate form and that has located thereon contact members 41 and used, it may bedesirable provide the the spring member rather that the design and construction of the memset forth. '-'I have illustrated a mo member 48.

ber 39 of the member .17 is such that they will properly cooperateas will be hereinafter ification in Fig.

7 of the drawing, which illustrates a portion only of the parts constituting a complete thermal relay. A supporting member 43 is of substantially U-shape, having upstanding portions 44-and 45 to which may be secured two substantially straight bimetallic-elements 46 and 47 at substantially the middle points thereof. An energy-storing or spring member 48,' tha t is of substantially circular sha e is provided. A toggle 'oint opera.- tive y associated with the mem r 48 com- .prises arms 49 and 51, the inner ends of which are pivotally connected by a pin 52. Adjustable contact members 53 and 54 are provided for the respective arms 49 and 51, which normally engage fixed contact members 55 and 56. 1

Anysuitable or desired means for effecting an o rative connection between the outer ends of the bimetallic elements 46 and- 47 and the member 48 may be provided, such, for instance, as by'reducing the lateral width of. the outer endsof the members 46 and 47 and causing them to project through suitable openings provided in the A loose connection between the bimetallic-elements and the spring member 48 is desirable but there should be no end pla between the two co-operating portions.

eferring more particularly to the deyice illustrated in Fig, 1 of the drawing, the bimetallic elements 15 and 16 are so arranged as regards the metal strip having the higher coefficient of expansion with an increase of temperature, that both spirals will tend to open or to unwind, thereby moving the member 17 downwardly in the plane of the paper as the temperature increases. The

As the temperature increases, the

' the broken gcontact members 25 and 27' and 26 and 28 This pressure between the cooperatm contact members increases until the mem er 17 has moved far enough to i to be limitedthereto as I may substitute a straighten out the toggle joint constituted spring member therefor; Y b

the arms 19 and 21, after which the togg e will snap into the osition illustrated b lines in ig. 1, the inner en s thereof enga 'ng an upstanding portion of amember 5 provided for that (purpose. When the to gle is in the osition lllllS- trated by the 'roken lines, a circuit that had been established through the cooperating contact members and the toggle has been interrupted. Conductors 58 and 59, havin one end thereof connected to the termina members 23 and 24, permit of connecting them to a suitable source of supply and to a qdevice to be controlled thereby.

. ticularly the outer ends thereof that the two arms are located in a straight line, the toggle will snap over to the other position, which is that shown in Fig. of the drawingi h' e toothed sectors 35 and 36 provide a means for varying the operative temperature at which disengagement of the cooperating contact members is efiected. A turning movement of the screw 32, in the member 29,

' causes a turning movement of the two sectors and therefore of the supporting osts 13 and 14. This varies the position 0 the inner ends of the bimetallic elements relatively to the outer ends, thereby varying the initial tensionand varying also the temperatur at'which actuation of the device will occur. As hereinbefore stated, I may use a spring member 39 in place of the toggle, the action of the device with such spring member being substantially the same as described above.

The modified form of device illustrated moreparticularly in Fig. 7 of the drawing operates in substantially the same manner as was hereinbefore described for the other of device. The two bimetallic elearelocated similarly as regards the form ments high expansion metal, that is, both bimetallic elements move in the same direction under the influence of a temperature increase or a temperature decrease. temperature surrounding the device illustrated in Fig. 7 increases, the bimetallic members 46 and 47 will bow upwardly, thereby initially increasing the pressure between the co-operating contact members until the toggle has been straightened, after which any further movement of the energystoring spring member 48 will cause a sudden disengagement between the co-operating contact members, the inner end portions of the arms 49 and 51 striking a sto member 61 provided for that purpose. xfhe bimetallic members 46 and 47 will tend to move in the opposite direction after the temperature thereof is reduced and the same sudden disengagement between the stop member and the toggle will be effected, while the engagement between the cooperating contact members will be made with a snap action.

The device embodying my invent'on thus provides a relatively simple and compact thermal relay that may be employed to control the temperature of a device or apparatus, that will be so moved as to cause engagement or disengagement of the cooperating contact members with a snap action only, and that will increase the pressure between the co-operating contact members until the instant of disengagement which, as above stated, is efiected with a snap action.

Various modifications may be made in the device embodying my invention without departing from the spirit and scope thereof, and I desire that all such modifications shall If the be included in the appended claims which are to be limited only by the prior art.

Iclaim as my invention:

1. In a thermal relay, the combination with a bimetallic member, of a spring member of substantially Ushape supported and actuated thereby, and means extending between the ends of said spring member and actuated thereby with a sna action only.

2. In a thermal relay, t e combination 'with a plurality of bimetallic members, of a spring member of substantially U-sha e having the outer ends of the bimetal ic members secured thereto and being supported thereby, co-operating contact members, and means supporting certain of said contact members operatively associated with said spring member, carried thereby and actuated by said spring member with a snap action only upon the occurrence of a predetermined temperature in said bimetallic members.

'3. In a thermal relay, the combination with a plurality of spirally-wound bimetallic members, of a spring member of substantially U-shape having the outer ends of the bimetallic members secured thereto and supported thereby; means operatively associated with said spring member, carried thereby and actuated by said spring member with a snap action only upon the occurrence of a predetermined temperature in said bimetallic members, and means operatively associated with said bimetallic members for varying the value of said predetermined temperature. y

In testimony whereof, I have hereunto subscribed my name this 11th day of June,

CHRISTIAN AALBORG. 

